Pyrethrin and dibenzyl phthalate insecticide



Patented Oct. 7, 1947 PYRETHRIN AND DIBE NZYL PHTHALATE Howard A. Jones, Orlando, Fla., and Raymond C. Bushland, Fort Worth, Tex assignors to United States of America, as represented by the Secretary of Agriculture No Drawing. Original application April 28, 1944,

Serial No. 533,267. Divided and this application September 19, 1944, Serial No. 554,864

3 Claims. 167-24) (Granted under the act of March 3, 1883, as

amended April so, 1928; 310 o. G. 757) o This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if

patented, may be manufactured and used by or We have prepared powders by dissolving a given amount of pyrethrum extract containing 20 percent pyrethrins and a given amount of dialkyl or substituted dialkyl phthalate in a 45 80 percent surviving or live lice after 24 hours.-

mutual, volatile solvent, mixing this with the desired amount of pyrophyllite, and subsequently removing the volatile solvent by evaporation. The resulting powders were dusted on underwear-cloth sleeves, the sleeves applied to the 50 is completely non-toxic. It will be noted from the human arm or leg, 25 recently fed, young adult lice introduced, and the sleeves taped to the body. The lice were therefore under essentially natural conditions. Several replicates of each for the Government of the United States of 5 treatment were made. Examinations "for living America f r sov t purposes without the and dead lice were made 24 hours after treatpayment to us oi'anvroyalty thereon. ment. In Table I and Table II are shown the This is a division of our copending application insecticidal results obtained in a series of tests for patent. Serial No. filed April 28, 1944. with powders prepared and tested as described.

The present invention relates to insecticidal The results are stated in terms of percent surp sitions. and more particula y to insectiviving lice after 24 hours exposure to the powcidal compositions containing Dyrethrum. dered insecticidal compositions.

The principal object or this invention is to N I provide a new and improved insecticidal coma 9 position.

v A further object is to enhance the effectiveness 2 percent phthalate oi pyreiliisrgim by combining with it an activator Phthalate Used Pl 00257 A] or syner llS 0 One l l0 It has long been known that pyrethrum is an pyrethrins pyrethl'ins eiiective insecticide. Pyrethrurn has certain dis k advantages, however, among which are its cost i' g 13 34 and the high concentrations needed to obtain Bi 21 3? complete kill of certain species of insects. }:g'g2{;}% 8

We have found that when pyrethrum is com ginn g bined with dialkyl or substituted dialkyl phthal- 25 igifigt? ates the resulting composition has an insecti- 2 2 3 1 46 cidal value far greater than would be expected pi ifi fi as a result of additive efiect of the components. gi-g g i f lf g f} g The high insecticidal efiicacy oi-the composition e Y is especially surprising in view of the fact that the aforementioned phthalates possess very little Table H insecticidal value in themselves. Thus, we have I found that powders comprisinga concentrated extract of pyrethrum flowers, a dialkyl or substi- Di'n'butyl Puma tuted dialkyl phthalate, and an inert carrier such as pyrophyllite are far more effective in pemntphthalate Wwntphthaltm killing body lice (Pediculus humanus corporis),

' l lfiy fiiiiii tfiiptfici ilifii tiififi than this. ttiiiit this.

is a high degree of activation of the pyrethrins 4 m 51 9 67 by these phthalates. 1

In control tests of this type without any insecticidal treatment, there is an average of about The concentrations of pyrethrins shown above (0.025 percent 'and 0.01 percent) when used alone gave the same average percent survivai as the controls. Thus, this concentration of pyrethrins v men grossly infested with lice.

I T 3 above tables that in general the phthalates tested were at the most only very slightly toxic,'even at the highconcentration or 2 percent. However, it will be seen from the table that in every case the composition comprising non-toxic concentration of pyrethrins' with a dialkyl or substituted dialkyl phthalate possessed a definitely greater insecticidal value (lower percentage of surviving or live lice) than the phthalate alone. For'example, 2 percent of dibutyl phthalate alone applied as described left 31 percent live lice in 24 hours. However, by combining this with a concentration of pyrethrins which in itself has no insecticidal value, a composition was obtained that gave complete control oi lice in 24 hours. Similar results have been obtained from tests on The aforementioned phthalates are cited merely as examples and it is not to be inferred that other esters of phthalic acid added to pyrethrlns cannot be used. Further, the above examples are not to be construed as limiting either the methods of preparation and application of this novel insecticidal composition or the kinds oi insects to which it may be applied. The proportions oi pyrethrum and phthalate may be varied over a wide range. The composition may be used either as a dust or as a spray with or without solvent. It may also be used in combination with other insecticides.

Having thus described our invention, we claim:

1. An insecticidal composition comprising pyrethrum and dibenzyl phthalate.-

2. An insecticidal composition comprising the extractives of pyrethrum flowers, dibenzyl phthalate andan inert diluent.

3. An insecticidal composition comprising not over 0.025 percent pyrethrins, not over 2.0 percent dibenzyl phthalate and an inert powdered carrier.

HOWARD A. JONES. RAYMOND C. BUSHLAND. 

